Aspheric lens grinder



March 29, 1966 L. H. BARRON ETAL ASPHERIC LENS GRINDER 3 Sheets-Sheet 1Filed Jan. 6, 1964 'Llulu 566058 62 4 mums INVENTORS LEE H. BA HRDNDOUG/J1 S L. MART/N A TTORNEY March 1966 L. H. BARRON ETAL 3,242,617

ASPHERIC LENS GRINDER Filed Jan. 6, 1964 3 Sheets-Sheet 2 i J5: 24 79 IFIG. 5.

A TTOR/VEY United States Patent 3,242,617 ASPEERIC LENS GRINDER Lee H.Barron, 4515 Alta Cauyada Road, La Canada, Calif., and Douglas C.Martin, Glendale, Calif. (9704 Mistletoe Road, Tujunga, Calif.)

Filed Jan. 6, 1964, Ser. No. 335,742 Claims. (CI. 51-58) This inventionrelates to a machine for grinding aspheric lenses, particularly largesized lenses.

One object of the invention is to provide a machine for grinding theoptical surfaces of internal or external aspheric lenses. Another objectis to provide a machine for grinding aspheric lenses which includes anonrotating cutter blade accurately shaped on its cutting edge to thecontour of the desired aspheric lens surface. Still another object is toprovide means for longitudinal oscillation of said cutter blade. Afurther object is to provide an aspheric lens grinding machine in whichthe lens is rotated and the cutter blade is not rotated but islongitudinally oscillated.

These and other objects are attained by our invention which will beunderstood from the following description, reference being made to theaccompanying drawing showing preferred forms thereof, in which FIG. 1 isa side elevational view of one form of our invention for grindingexternal aspheric lens surfaces with parts broken away to show certaindetails in section;

FIG. 2 is a cross-sectional view taken on the line 2-2 of FIG. 1;

FIG. 3 is a fragmentary cross-sectional view taken on the line 3-3 ofFIG. 2;

FIG. 4 is a fragmentary cross-sectional view taken on the line 4-4 ofFIG. 1;

FIG. 5 is a fragmentary cross-sectional view taken on the line 5-5 ofFIG. 1;

FIG. 6 is a side elevational view, with parts broken away, as shown insection, showing another form of our machine for grinding internalaspheric lens surfaces; and

FIG. 7 is a cross-sectional view of the same, taken on the line 7-7 ofFIG. 6.

Referring to the drawings, particularly FIGS. 1 to 5, a work table 11 isattached by bolts 12 to a turntable 13, whose hub 14 is operativelyattached to the vertical drive shaft 15 which is mounted at its lowerend in a pillow block bearing 16, and also in a thrust bearing 17 whichare disposed in operative position on a rigid frame 18. An intermediatebearing 16a attached to the frame 18 above the pulley 19 is alsoprovided. Other bearings adjacent the upper extension of the shaft areprovided and will be described later. Intermediate the bearings 16 and16a, a drive pulley 19 is mounted on the shaft 15, the pulley beingdriven by the belt 20 which is actuated by a variable speed rotary powermeans (not shown).

The drive shaft 15 extends above the turntable 13 so that its upper end22 is above the cutter frame 23, the latter being a platelike structurerotatably suspended on a steel ball bearing 29 positioned in a sphericalcavity 30 in the upper end 22 of the shaft 15, as will be more fullyexplained below.

The cutter frame, numbered 23 generally, is a laminated structurecomprising a front plate 24, a back place 25, and a spacer 26 whichholds the front and back plates apart, there being machine screws 27 atseveral locations for holding the laminated structure together. Portionsof the spacer 26 are removed to form recesses for the cutter bladeholders 46 and 47, and other parts as will be indicated.

The cutter frame 23 is disposed diametrically in relation to the driveshaft 15, and to the turntable 13 and the workpiece (the lens blank)which is mounted thereon. The cutter frame 23 is suspended on a steelball 29 which is seated in a cavity 30 on the upper end of the driveshaft 15, by a saddle frame 31 whose lens 32 extend over the oppositesides of said cutter frame, enclosing bearing assembly 34 for the upperend portion of the drive shaft 15. A vertical adjusting screw 35 isvertically mounted in a threaded collar 38 on the saddle frame 31, therebeing a cavity 36 in the end of the screw to engage the steel ball 29,and a lock nut 37 on the screw to hold the screw in a selected verticalposition.

The bearing assembly 34 consists of oppositely arranged mounting wings39 which are disposed in a corresponding recess provided in the spacer26 between the front and back plates 24 and 25 of the cutter blade frame23, and attached thereto by through bolts 42. An upper sleeve bearing 49and a lower sleeve bearing 41 are held in position on the drive shaft 15by the edges of the wings 39.

The entire cutter blade frame 23 is prevented from r0- tating on thesteel ball 29 by the abutment bracket 43 which is mounted on a topmember of the machine frame 13.

The cutter blade holders 46 and 47 are substantially alike, beingarranged in diametric alignment with relation to the work piece 10 andthe work table 11. Each holder, for example 46, consists of a generallyarcuate plate-like body which slidably fits between the front plate 24and the back plate 25 in a recess provided by the spacer 26. The inneredge of the holder 46 (and 47) corresponds generally to the contour ofthe roughed-out work piece 10, and an arcuate diamond coated tool 49 isattached to the holder 46 (and 47). Longitudinal slots '77 and '78 areprovided in the forward arcuate edges of the holders 46 and 47, and thediamond coated edge contoured tools 49 are held in accurately adjustedposition by the shouldered screws 79 whose heads are recessed in holeson one wall of the slots, and threaded holes in the opposite wallbordering the slots 77 and 78. The front plate 24 at its lower outercorner is provided with an outwardly extending bracket 51 whose endsurface abuts a micrometer screw 52 which is operatively mounted on boss53 which is attached by screws 54 to the cutter blade holder 46 for thepurpose of accurately measuring the depth of cut on the work piece.

The cutter blade holders 46 (left) and 47 (right) are supported forsliding movement laterally between the front plate 24 and the back plate25, and are held against outward movement respectively by the feederscrews 56 and 57 which are mounted in threaded spacer blocks 58 and 59held between the front plate 24 and the back plate 25. Lock nuts 69 and61 are provided on the feeder screws 56 and 57 respectively. Tensionsprings 62 and 63 are provided respectively between the spacer blocks58, 59 and the cutter blade holders 46 and 47.

The cutter blade holders 46 (left) and 47 (right) are supportedvertically by the suspending spring 64 and 65 respectively which areattached respectively to the left and right mounting wings 39. Theholders 46 and 47 are also positioned by the stops 66 and 67respectively which are rectangular blocks mounted respectively on pivots68 and 69 which are mounted by mounting plates respectively '71) and 71(not shown) to the front and back plates 24 and 25, there beingrectangular recesses respectively 72 and 73 in the cutter blade holders46 and 47, which recesses are of larger dimensions than the stops 66 and67.

The cutter blade holders 46 (left) and 47 (right) are oscillated in adirection tangential to the abrasive surface of the cutter blades ortools 49. The oscillating means, in general, consists of eccentricallymounted shafts on each holder, and means for rotating them. This meansacts upon a rectangular follower block (which is confined in a recess inthe spacer for movement only at right angles to the oscillationmovement), to move the holders in tangential oscillation. For each ofthe cutter blades 46 and 47, there is provided respectively shafts 31and 82, which are each mounted in sleeve bearings 83 in the front plate24 and back plate 25. An eccentric 85 is provided on the portion of theshafts between the plates 24 and 25, and a follower block 86 is mountedon the eccentric 85. A rectangular opening 87 in the holder 46 isprovided to receive the follower block 86, the edges of this openingslidingly engaging the block on two sides, but permitting movement atright angles to the tangent to the curve of the cutter blades 49.Sprockets 88 and 89 are mounted respectively on the oscillating shafts81 and 82 for the rotation thereof, both sprockets extending forwardlyfrom the front face of the front plate 24. An electric motor 90, havingmeans for speed reduction, is mounted on the edge of the cutter bladeframe 23, a drive sprocket 91 projecting in driving alignment with thesprockets 88 and 89, a drive chain 92 being arranged to operatively passover the motor drive sprocket, the shaft sprockets 88 and 89, and idlersprocket 94 mounted on the front plate 24 in position to provide anoperable path for the chain drive 92.

The cutter blade or tool 49 consists of a metal base whose arcuate edgeface is coated with diamond particles which are bonded together and toeach other by an electroplate of nickel, the edge surface being formedduring electroplating by a template whose curvature accurately coincideswith the aspheric surface of the lens surface which is to be generatedon the work piece.

Another form of this machine shown in FIGS. 6 and 7 may be used togenerate an internal lens surface. An internal lens work piece 10A ismounted on a turntable 11A, as in the previously described machine form,and the work piece is rotated by means as previously described. Theplate-like cutter frame 23A is suspended on a steel ball 29A from thetop of the main drive shaft 15A. In the form shown in FIGS. 6 and 7 asingle radial cutter frame 23A is mounted on sleeve bearings around theshaft 15A, and it consists of a front plate 24A, a back plate 25A, and aspacer plate 26A bolted together, with recesses in the spacer plate 26Afor the cutter blade holder 46A, and other parts as will be described.As before, contoured diamond coated cutter or tool 49A is mounted bybolts in a peripheral groove in the cutter blade holder 46A. The cutterblade holder 46A is held in a rectangular stop 66A which is mounted onthe pivot 68A in mounting plate (not shown but like 70) and is arrangedto slide in a rectangular recess 72A in the spacer plate 26A. Thetension spring 62A holds the lower end of the cutter blade holder 46Atoward the shaft 15A, and the spring 64A which is attached to an upwardextension 51A of the cutter blade holder 46A and to a bracket 101 on thesuspending frame 31A. The cutter blade holder 46A and the cutter tool49A are oscillated in a direction tangential to the cutting edge of thetool by means of an eccentric oscillating shaft 81A which is mounted insleeve bearings in the front plate 24A and the back plate 25 of thecutter blade frame 23A. An eccentric (similar to 85) is provided in aportion of the shaft between the plates, and a follower block 86A ismounted on the eccentric. A rectangular opening (similar to 87) in thespacer plate 26A is provided to receive the follower block 86A, theedges of this opening slidingly engaging the block on two sides, but notpermitting movement at right angles to the tangent to the curve of thecontour cutter blade 49A. A sprocket 88A is mounted on the oscillatingshaft 81A for its rotation, the sprocket extending forwardly from thefront face of the front plate 24A. An electric motor 90A, having meansfor speed reduction, is mounted on the supporting frame 31A, a drivesprocket 91A projecting in driving alignment with the sprocket 83A, adrive chain 92A being arranged operatively over the motor drive sprocket91A, the oscillating shaft sprocket 88A and an 4 idler sprocket 94A alsomounted on the supporting frame 31A.

A feeder screw 56A is provided on the upper corner of the cutter bladeholder 46A, a threaded block 58A being mounted on the back plate 25A anda lock nut 60A being provided. A micrometer 52 is similarly mounted sothat accurate measurement of the amount of the cut on the work piece 10Amay be made.

The manner of operating the lens grinding machine will be apparent fromthe above description. The spherical blank for the lens is rough shapedby conventional forming means, and is mounted, by cementing, on the worktable 11,,and after the finishing cuts have beenmade by the diamondcoated contour tool in this machine, the surface is given a finalpolishing by conventional lens polishing procedures. Water or othercutting liquid may be supplied on the cutting area. The tangentialoscillation of the cutter is regulated so that any cutting ridges areremoved and a smooth surface is generated.

The objectives set forth in the beginning have been attained.

We claim:

1. A machine for grinding an aspheric lens surface on a lens work piececomprising a rigid supporting frame including a base and a platformdisposed above said base; a vertical shaft mounted in hearings on saidframe and extending above said paltform; means for rotating said shaft;a turntable mounted axially on said shaft above said platform, saidturntable being adapted to support and rotate said lens work pieceattached thereto, said work piece having an axial hole therethrough forsaid shaft; a cutter blade frame including a suspending member mountedon a bearing adjacent the upper end of said shaft, means for preventingthe rotation of said cutter blade frame in relation to said supportingframe; a cutter blade holder oscillatably mounted on said cutter bladeframe; a contoured diamond-coated edge cutter blade attached to saidholder; and means for oscillating said cutter blade holder and saidcontoured cutter blade in an arcuate direction relative to the asphericlens surface of said Work piece during the rotation and grinding of saidwork piece.

2. A machine for grinding an aspheric lens surface on a lens work piececomprising a rigid supporting frame including a base and a platformdisposed above said base; a vertical shaft mounted in bearings on saidframe and extending above said platform and having an axially alignedball cavity in its upper end; means for rotating said shaft; a turnablemounted axially on said shaft above said platform, said turntable beingadapted to support and rotate said lens work piece attached thereto, thework piece having an axial hole therethrough for said shaft; a cutterblade frame including a suspending member telescoped over the upper endof said shaft and suspended on a steel ball in the cavity in the upperend of said shaft, and a radial frame member attached to said suspendingmember, said suspending member including cylindrical bearings aroundsaid shaft; means for preventing the rotation of said cutter blade framein relation to said supporting frame; a cutter blade holder oscillatablymounted on said radial cutter blade frame member; a contoureddiamondcoated edge cutter blade adjustably attached to said holder; andmeans for oscillating said cutter blade holder and said contoured cutterblade in an arcuate direction relative to the aspheric surface of saidwork piece during the rotation and grinding of said work piece.

3. The machine for grinding aspheric lens surfaces as defined in claim1, in which the means for oscillating the cutter blade holder consistsof an oscillating shaft mounted for rotation on said cutter blade holderframe, said oscillating shaft having an eccentric portion engaging afollower-block positioned in a rectangular recess in said cutter bladeholder frame, said recess being dimensioned to permit sliding movementof said block in a direction at right angles to the tangential directionof oscillatory movement, and rotary means including'a motor mounted onsaid cutter blade holder frame, a drive sprocket on said motor, asprocket on said oscillating shaft, idler sprockets, and a chainoperatively connecting said sprockets.

4. A machine for grinding an external aspheric lens surface on a lenswork piece comprising a rigid supporting frame including a base, and aplatform disposed above said base; a vertical shaft mounted on bearingson said frame and extending above said platform and having an axiallyaligned ball bearing cavity in its upper end; means for rotating saidshaft; a turntable mounted axially on said shaft above said platform,said turntable being adapted to support and rotate work piece attachedthereto, the work piece having an axial hole therethrough for saidshaft; a cutter blade frame including a tubular suspending membertelescoped over the upper end of said shaft and suspended on a steelball in the cavity in the upper end of said shaft, and a pair ofdiametrically opposed radial frame members attached to said tubularsuspending member, said suspending member including cylindrical bearingsaround said shaft; means for preventing the rotation of said cutterblade frame in relation to said supporting frame; cutter blade holdersoscillatably mounted on each of said radial cutter blade frame members;contoured diamondcoated edge cutter blades attached to each of saidholders; and means for simultaneously oscillating said cutter bladeholders and said contoured cutter blades in an arcuate directionrelative to the aspheric surface of said work piece during the rotationand grinding of said work piece.

5. The machine for grinding external aspheric lens surfaces as definedin claim 4, in which the means for oscillating each of the cutter bladeholders consists of an oscillation shaft mounted for rotation on each ofsaid radial frame members, said oscillataing shaft having an eccen tricportion engaging a follower block positioned in a rectangular recess insaid radial cutter blade frame member, said recess being dimensioned topermit sliding movement of said block in a direction at right angles tothe tangential direction of oscillatory movement, and rotary meansincluding a motor mounted on one of said cutter blade frame members, adrive sprocket on said motor, a sprocket on each of said oscillatingshafts, idler sprockets, and a chain operatively connecting saidsprockets.

References Cited by the Examiner UNITED STATES PATENTS 644,445 2/1900Nerz 5167 1,238,612 8/1917 Wilson 5158 2,271,334 1/1942 Fosdick 51-673,169,350 2/1965 Corman 5158 LESTER M. SWINGLE, Primary Examiner.

ROBERT C. RIORDON, Examiner.

J. A. MATHEWS, Assistant Examiner.

1. A MACHINE FOR GRINDING AN ASPHERIC LENS SURFACE ON A LENS WORK PIECECOMPRISING A RIGID SUPPORTING FRAME INCLUDING A BASE AND A PLATFORMDISPOSED ABOVE SAID BASE; A VERTICAL SHAFT MOUNTED IN BEARINGS ON SAIDFRAME AND EXTENDING ABOVE SAID PLATFORM; MEANS FOR ROTATING SAID SHAFT;A TURNTABLE MOUNTED AXIALLY ON SAID SHAFT ABOVE SAID PLATFORM, SAIDTURNTABLE BEING ADAPTED TO SUPPORT AND ROTATE SAID LENS WORK PIECEATTACHED THERETO, SAID WORK PIECE HAVING AN AXIAL HOLE THERETHROUGH FORSAID SHAFT; A CUTTER BLADE FRAME INCLUDING A SUSPENDING MEMBER MOUNTEDON A BEARING ADJACENT THE UPPER END OF SAID SHAFT, MEANS FOR PREVENTINGTHE ROTATION OF SAID CUTTER BLADE FRAME IN RELATION TO SAID SUPPORTINGFRAME; A CUTTER BLADE HOLDER OSCILLATABLY MOUNTED ON SAID CUTTER BLADEFRAME; A CONTOURED DIAMOND-COATED EDGE CUTTER BLADE ATTACHED TO SAIDHOLDER; AND MEANS FOR OSCILLATING SAID CUTTER BLADE HOLDER AND SAIDCONTOURED CUTTER BLADE IN AN ARCUATE DIRECTION RELATIVE TO THE ASPHERICLENS SURFACE OF SAID WORK PIECE DURING THE ROTATION AND GRINDING OF SAIDWORK PIECE.